In turbomachines, the injectors can be disposed radially on the inside and on the outside of the nozzles, and injector feed enclosures with connection devices for making connections with the nozzles can also be disposed radially on the inside and on the outside of the nozzles.
Known connection devices are constituted by cylindrical bushings having their ends engaged in orifices in the wall of the nozzle and in the feed enclosures, and which are capable of sliding in said orifices. Axial retaining means are provided to prevent the bushings from escaping from the orifices and they are formed firstly by flaring one end of each bushing and by providing an intermediate flange mounted in the under-nozzle feed enclosure for the bushings mounted in the internal chambers, and secondly by using retaining rings which, for retention purposes, require an annular groove to be machined inside an intermediate bushing housed in the wall of the over-nozzle feed enclosure, and in which a portion of the connection device is engaged, for the bushings mounted in the external chambers.
Those devices of multiple shapes increase the risk of error when it comes to selecting the appropriate connection device for mounting on the turbomachine, and prevent the cost of manufacturing such devices being optimized. In addition, each additional part of a different shape constitutes a new reference that must be managed, e.g. in terms of duration such as manufacturing duration or transport duration; in terms of availability, e.g. whether parts are available in stock for making or maintaining turbomachines; or indeed in terms of quality, which needs to be monitored in order to comply with the strict specifications that are needed in the field of aviation. Managing each new part is expensive.
In addition, the weight and cost constraints to which turbomachines must comply require manufacturers to make connection devices and means for preventing such devices moving axially that are simultaneously simple, lightweight, and inexpensive. The known technique for satisfying the above-mentioned constraints consists in achieving axial retention of the connection device towards the rotor of the turbomachine by means of an intermediate plate disposed inside the under-nozzle feed chamber, which plate also serves to maintain sealing of the feed enclosure. The intermediate plate is shaped to present a bearing surface that is to come into contact with the axial end of the connection device that is adjacent to the rotor of the turbomachine.
Although that technique for preventing movement is very simple, it suffers from the drawback of reducing the cross-section of the feed enclosure where the connection device opens out to the inside of the feed enclosure. That reduction leads to significant head losses on the flow of gas leaving the connection device. Such head losses reduce the feed pressure to the injectors, and consequently the quality of the injection, since it needs to be performed under high pressure.
In addition, using an intermediate plate to form an axial abutment increases the weight of the feed enclosure, and consequently increases the mass/power ratio of the turbomachine, whereas attempts are always made to reduce said ratio.